EPIDEMIOLOGICAL INVESTIGATION AND TRANSMISSION RISK SCORING OF SWINE INFLUENZA IN PHILIPPINE SMALLHOLD PIG FARMS USING LABORATORY AND FARM-LEVEL INDICATORS

Abstract

This study investigated the prevalence, risk factors, and transmission risk of swine influenza (SI) in pigs from smallhold farms in the Philippines due to its possible risks to animal and public health. A total of 425 blood and 407 nasal swab samples were collected from slaughterhouses in 21 provinces and analyzed using competitive enzyme-linked immunosorbent assay and real-time reverse transcription polymerase chain reaction (qRT-PCR) assay to detect SI antibodies and viral RNA, respectively. Results revealed an overall seropositivity of 22.8% (97/425) and qRT-PCR positivity of 0.5% (2/407). Water treatment, vaccination, and swill feeding positively influenced seropositivity, while the distribution of native pigs and proximity of farms to residential areas had negative impacts. The semi-quantitative risk scoring of SI transmission demonstrated that Cebu (16.2/19.1) was considered an extreme-risk area, while Davao del Sur (15.2/19.1) was classified as a very high-risk area. The remaining 19 provinces had moderate (n=5), low (n=12), and very low (n=2) risks. These findings provide local epidemiological data on SI and emphasize the significance of continued surveillance and strict biosecurity to mitigate the potential risks of SI.